In the electric power steering device, which is the steering device of a vehicle, to exert the steering assistance force by a rotational force of the electric motor, the steering assistance force generated by the electric motor is exerted to a steering shaft and the like of the steering system via a reduction gear.
Conventionally, since noises are included in a steering torque signal detected by a steering torque sensor, the electric power steering device has to include a noise removal means for removing the noises.
For this reason, as the noise removal means in the conventional electric power steering device, for example, a smooth filter is appropriately provided for smoothing quantization errors generated at the time of AD conversion of converting various analog signals in the electric power steering device, so as to smooth the quantization errors and suppress torque ripples caused by the quantization errors (for example, see Patent Literature 1).